In the women's 50m butterfly, Australian Marieke Guehrer was a surprise winner in a time of 25.48, beating Zhou Yafei by nine hundredth of a second.

Third place went to Norwegian Ingvild Snildal, who was a further hundredth behind.

Guehrer was totally shocked when she got out of the water. 'Are you sure that I won, it must be a mistake. They must have made a mistake,' she asked an Australian swimming official.

In the semi-finals of the women's 50m breaststroke Australian Sarah Katsoulis led the field into the final with a time of 30.33, beating Annamay Pierse by seven hundredth of a second.

Cate Campbell topped the rankings in the women's 50m freestyle ahead of Marleen Veldhuis. The Briton Campbell swam 24.08, 0.12 seconds faster than the Dutch woman.

German 100m gold medallist and world record holder Britta Steffen had the third-fastest time, while 42-year-old Dara Torres also made the final as eighth-fastest.

Still on the programme for Saturday evening are the finals of the women's 800m freestyle and 4x 100m medley and the semi-finals of the men's 50m backstroke.